This is not a good thing in my opinion. The Filipinos, left on their own, would slaughter every last Muslim bastard involved in the fight, until none were left. Now, with U.S. involvement, they will be constrained by ridiculous R.O.E.s and U.N. bullshit.
I think we have to admit that the track record of the U.S. in terms of fighting a war, is abysmal after WWII. It is always nice to have the technology and money that America has to offer, but in terms of getting them involved in fighting a real war, if I were the Philippines, I would rather be on my own. The U.S. knows how to lose a war. The U.S. knows how to fight a stalemate war for 25+ years. But, since 1945 America has never "won" any war.
Rodrigo Duterte el Audaz y el Valiente, would be wise to keep America out of the actual fighting and out of the prosecution of the war effort, if he intends to actually 'win' the war. All America will do is to bog him down with bullshit and he will be fighting this scum for the next 100 years.